Dental implant for the securement of fixed dental prostheses

ABSTRACT

A dental implant that serves as its own cutting tool for forming a T-shaped slot in a human tooth to receive the implant, comprises a flat circular wheel having cutting teeth on its periphery. The wheel has a diameter that is a plurality of times its thickness. An elongated shaft is secured coaxially to the wheel and has milling surfaces thereon that extend from the wheel a distance which is a plurality of times greater than the thickness of the wheel and a plurality of times greater than the diameter of the milling surfaces. The diameter of the wheel is a plurality of times greater than the diameter of the milling surfaces. A portion of the shaft extending beyond the milling surfaces in a direction away from the wheel permits the releasable securement of the implant to a dental drill.

The object of the invention is a dental implant for the fixing of fixeddental prostheses.

The implant is a substructure generally metallic used for supporting adental prosthesis. It allows to replace the teeth as natural pillars bymechanical pillars placed either into the mandibula or the maxilla.

The essential in the positioning of a dental implant is to obtain animmediate blocking up into the bone. The slightest mobility of theimplant inside the bone leads eventually to rejection. Once the implantis set into the bone, a tapped ring or screw is set onto the outsidepart which is generally a threaded rod. On this tapped ring or screw,the dental prosthesis is fixed with a cement.

The state of the art may be defined by the French patent registered onJune 12, 1972 under Nr No. 72 21113 and published on Jan. 2, 1974 underNr No. 2.188.445.

The patent describes an endo-osseous anatomic implant and its insertionprocess, including a grid topped by one or several rods called"false-stump" for the fixing of prostheses, an implant characterized bythe fact that the polygon of support of the grid is mainly disposed in ahorizontal plane, this grid being shaped so as to be set into themandibula or the maxilla, according to one or several planes issued fromor close to an horizontal plane, so that the grid goes into a trenchwith one or several approximately horizontal planes made on thevestibular, lingual or palatal side of the maxillar body considered,while the false-stump(s) go(es) at the same time into as many verticalpassages cutting the plane(s) of the approximately horizontal trench.

Other implants known as LINKOW's strips can also define the state of theart. These strips are characterized by a strip-shaped hooking partcomposed of several arched hooking legs ending with feet.

This part as a whole tends to allow the osseous tissue to graduallyimbricate between legs and feet so as to fix the implant solidly.

The conception of these implants and the way they are positionned aresubject to many drawbacks. The boring of the bone on a vertical planeand a sometimes wide diameter, is necessarily deep to mask the wholeheight of the implants. Now the bone, very often, does not offersufficient height and the implants cannot pass round the obstacles suchas sinuses, nasal fossae, nerves, the boring having to be effectedalmost always vertically.

Consequently these types of known implants cannot be adapted to variousbony structures. Moreover, these implants, essentially inserted on avertical plane, present bad characteristics of transmission of theforces imposed on them. They work essentially on edge and have a strongtendency to self-bore under the pressures exerted by mastication.

These implants, inserted on a vertical plane, resist badly the tensile,driving in and side stresses in the four directions.

The positioning of these implants is an awkward operation. It isnecessary to form a groove corresponding exactly to the dimensions ofLINKOW's strips.

The positioning of an implant described in JUILLET's patent requires adrilling which now can only be achieved in two phases of intervention: avertical drilling followed by an horizontal drilling or reversely, andthis being achieved with tools used separately.

On the other hand, the bone drilling tools are made of either tungstenor steel, or agaon of another material which is always different fromthat of the implant itself. There is a risk of polymetallism when theimplant is placed into its site of lodging. As a matter of fact, theimplant being made of titanium, the titanium will interfere with that oftungsten or steel or any material other than titanium.

It is unanimously admitted that, when drilling the bone with a metallicpart, metallic particles always remain in the area (osseous territory).So, both the tool and the implant must be manufactured with the samemetal to avoid a bi-metallism generating tissue lesion.

The invention tends to solve all these drawbacks. Especially, theinvention tends to ensure a faultless primary fixation owing to thepreciseness with which the lodging of the implant is cut into the bone.

The implant according to the invention is characterized by the fact thatthe tool necessary to cut the lodging can stay in place and be used as adental implant. The compulsory consequence is that the implantcorresponds exactly to the lodging formed by the tool.

This implant has a double function:

1. It is used as an artificial root in replacement of the missingnatural dental pillars. It is its main and final function.

2. At the same time, it can be its own boring tool. its indentedstructure (on the wheel) and milled, on the axis, allows this implant,once it is placed on a rotating instrument (owing to its smooth"junction" tip), to be used as a drilling tool of the implant lodging(maxilla) which will receive it.

The smooth tip prolonging the milled part and the possible threading wasspecially elaborated to adapt directly on a high speed turbine or micromotor. In case of need a supplementary notch can also been provided onthe tips of the shafts to receive the blocking clamps of drills at slowand medium speed and hand tools.

The characteristic of this tool-implant is to achieve in one singlephase a micro-osteotomy by drilling. simultaneously in the horizontaland vertical planes, in other words in two perpendicular planes.

Another advantage of the tool-implant: this drill-tool rotates (onceclamped onto the turbine, the micro-motor or the drill or the hand tool)around its axis.

When placing it laterally against the bony wall, the practitionner, in astraight-line translation movement, allows the intra and trans-osseouspenetration in a plane parallel to that of the indented wheel, for thebase or wheel. At the same time, he achieves a simultaneous penetrationof the rod in a plane perpendicular to the base or wheel.

According to another conception, the tool can be recovered and animplant corresponding to the formed lodging can be positioned in thiscase, the implant to be positioned has characteristics slightlydifferent from the tool in order to be "forced" into the said lodging.Consequently, the implant profile is identical to that of the tool butsome parts are not sharpened, others are thicker to avoid any mobilityof the implant in its lodging. The base of the wheel has a smooth edgeinstead of being indented. The rod can be either smooth or threaded.

The tool implant according to the invention consists of a rod with atone end, a smooth part used as junction tip prolonged by a threaded partallowng to fix a tapped ring or screw. The junction tip of the toolimplant may have an adaptation clamp for the drills and hand tools. Atthe other end of the said rod, at least one indented wheel is placed:the said wheel is perpendicular to the longitudinal axis of the rod toallow horizontal drilling while the vertical drilling is achieved by apart of the rod the base of which is milled from at least one of theindented wheels.

The milled part of the rod which is set at the base of the said rod,from the indented wheel, is composed of circular furrows or grooves theedges of which are sharpened. So this part can cut vertically when therod is operated by a rotating instrument.

The grooving was elaborated in a special way so as to obtain a maximumcutting action for a minimum over-heating and trauma where the osseoustissue is concerned. A notching in the horizontal direction allows thechips to be cleared out, while lowering the over-heating of the osseoustissue.

The indented wheel has sharpened teeth on its periphery. It can cuthorizontally when the said rod is operated by a rotating instrument.

The indented wheel may have holes which allow reducing the weight of thematerial of the tool-implant, without reducing the mechanical qualities.

The insertion process of such a tool-implant consists in helving theturbine onto the junction tip of the said tool-implant, as soon as itrotates; a micro-osteosection by drilling can be achieved in one phase,at the same time in a horizontal and vertical plane, that is to say intwo perpendicular planes. The number of wheels determines the number ofhorizontal planes.

The tool-implant is placed in the lodging formed by the slotcorresponding to the profile projected laterally of the tool or thetool-implant. The tool-implant or the independant implant is insertedlaterally into the said slot preferrably on the vestibular side so thatonly the end of the rod opposite to that of the wheel protrudes from thebone edge. The rod is cut at required height to receive the screw ortapped ring. There is no adjusting needed since both tool and implantform one part. Before its final biological blocking by regeneration ofthe bone around the implant and specially around the milled part, thesaid implant is perfectly stable owing to the quality of the technicalcharacteristics of its lodging.

According to another conception, the implant is independent from thetool.

The tool according to the invention is characterized by the fact that itpresents all the technical characteristics of the tool-implant describedhere above.

The independent implant properly speaking, presents all the technicalcharacteristics of the tool, with the essential technical differenceshereunder:

In the milled part, the circular furrows or grooves are less sharpenedthan those of the tool, so the edges are less sharp. In some shapes,they do not exist. Consequently the body is either smooth or threaded.

The circumference of the wheel perpendicular to the longitudinal axis ofthe tool is smooth, so, it presents no cogs. The smooth wheel isslightly thicker than the indented wheel of the tool so as to be"forced" into the lodging created by the indented wheel of the tool.

According to a preferred conception, the rod of the tool and implantand/or tool implant has only one wheel. According to another conception,the wheel perpendicular to the longitudinal axis of the rod is removableand thus can be fixed to the end of the said rod when necessary.

According to another conception, two parallel wheels can be mounted ontothe same rod. This conception is not represented in the drawings.

The attached drawings are given merely as an indication and are notrestrictive; they will make the understanding of the invention easy.They show some preferred conceptions, according to the invention.

FIG. 1 shows a side view of the tool or the tool-implant.

FIG. 2 is a section view of the tool or the tool-implant according toaxis BB represented in FIG. 1.

FIG. 3 is a side view of the implant independent from the tool.

FIG. 4 is a section view according to axis AA of the implant independentfrom the tool, as shown in FIG. 3.

FIG. 5 is a schematic view of a rotating tool cutting an implant lodginginto the maxilla.

FIG. 6 is a schematic view of a tool which, by rotating according toArrow F1, has bored the lodging or site for the implant into themaxilla.

FIG. 7 shows that the tool implant or the tool can go laterally into andout of the lodging of the implant according to Arrows F2, F3. Theimplant has just to be inserted laterally into the slot created by theprofile of the tool-implant or the tool.

FIG. 8 represents an independent implant about to be forced into itslodging according to Arrow F4. It should be noted that the furrows orgrooves are not sharpened, that the smooth wheel is thicker than theindented wheel of the tool, which ensures a perfect mobility of theimplant in its lodging or site.

FIG. 9 is a schematic view of an implant independent from the tool,positioned in its implant lodging; the end of the implant is equippedwith an attaching device, as for instance a threading which allows thefixing of the body; on that tapped ring or screw the dental prosthesiswill be cemented.

FIG. 10 is a perspective view of a lower jaw showing positionedimplants, with their tapped ring or screw ready to receive theprosthesis, a tool in operation, a lodging or site for implant.

FIGS. 11, 12, 13 show the operating of the tool-implant boring into thebone a slot corresponding to its profile.

FIG. 14 shows how the junction tip allows the fixing of the tool or thetool-implant into the spindle of the turbine.

FIG. 15 shows a turbine in operation with air and water jets forcooling.

The tool-implant 1 according to the invention is composed of a part 2used as a vertical drill and another part 3 perpendicular to thelongitudinal axis and used as drill-wheel 5. Part 2 is equipped at itsbase 4 with an indented wheel 5 perpendicular to the longitudinal axisand at its other end 7 with a fixing device 6 which allows the fixing ofthe tapped ring or screw S on which the dental prosthesis 9 and/or asmooth part used as junction tip 11 are positioned.

The tool-implant 1 is composed of only one part, consisting of a rod 10having a junction tip 11 which helves into the spindle of turbine 23;this junction tip 11 may have at its end 7, a fixing device 6 whichallows the positioning of a tapped ring or screw 8. The said fixingdevice 6 can be for instance a threading of this end 7 of thetool-implant 1. The profile of the tapped ring or screw is special. Itconsists of two inverted truncated cones, a and b, a large and a smallone.

"a" is the large truncated cone: it is intended to receive the tooth orthe prosthetic superstructure.

"b" is the small truncated cone: it is contiguous to the gum and isshaped so as to allow the gum tissue to take the exact shape of itscircumference. This limits the risks of irritation and retention of thebacterial plaque and food remains. The inverted truncated cone bsuppresses any overhanging and thus the blocking of the substances atthis level. This shape takes the most up-to-date periodontal conceptsinto account.

The other end 2 of the tool-implant 1 includes a milled part 12 endingwith an indented wheel 5 perpendicular to the longitudinal axis.

The milled part 12 presents circular furrows or grooves 13 the edges ofwhich are sharpened and form mills 22 grooved in the direction of thelongitudinal axis of the rod, so as to obtain a maximum cutting actionwith a minimum over-heating and osseous trauma. A notching in thehorizontal direction allows the chips to be cleared out while lowerngthe over-heating of the osseous tissue.

Wheel 5 has sharpened teeth 14 on its periphery.

Wheel 5 may have for instance four holes 15 which allow reducing theweight of the material of the tool-implant and this, without reducingthe mechanical qualities. The osseous tissue grows through the implantthrough these holes and ensures part of the final biological blocking;the imprisonment of the base plus rod set by the bone ensures the restof the blocking.

According to another conception, the implant is independent from thetool.

1. The tool has all the technical characteristics described above forthe tool-implant (see FIG. 1).

2. The implant properly speaking 16 has all the technicalcharacteristics described above for the tool-implant 1 with theessential technical differences here-under (see FIG. 3):

the milled part 12 no longer has a vertical cutting action, so the edgesof the furrows or grooves 17 are less sharp than for mills 22. This partno longer has a cutting action, but only a retaining action. Thuscircular furrows 17 are less sharpened, the edges are less sharp,

the smooth wheel 18, perpendicular to the axis of the rod does not haveany teeth on its periphery, moreover, it is thicker at 19 than theindented wheel 5 of tool 1, so as to force-fit the implant lodging 20created by the indented wheel 5 of tool 1.

FIG. 11 shows the cutting action of the tool or tool implant into thebone to achieve a slot corresponding to the implant lodging or site 20.This lodging 20 corresponds to the profile projected laterally of thesaid tool or tool implant to be inserted laterally into the said slot.Only the end 7 of rod 10 opposite to indented wheel 5 or the smoothwheel 18 perpendicular to the longitudinal axis of the said rodprotrudes from the edge of bone 21. FIG. 9 shows implant 1 ortool-implant 16 positioned equipped with the prosthetic tooth 9 afterrod 10 has been cut to the required height and has received thecorresponding threaded screw 8.

What is claimed is:
 1. A dental implant that serves as its own cuttingtool for forming a T-shaped slot in a human tooth to receive theimplant, comprising a flat circular wheel having cutting teeth on itsperiphery, the wheel having a diameter that is a plurality of times itsthickness, and an elongated shaft secured coaxially to the wheel, theshaft having milling surfaces thereon that extend from the wheel adistance which is a plurality of times greater than the thickness of thewheel and a plurality of times greater than the diameter of said millingsurfaces, the diameter of the wheel being a plurality of times greaterthan the diameter of the milling surfaces, a portion of the shaftextending beyond said milling surfaces in a direction away from thewheel to provide means for releasably securing the implant to a dentaldrill.
 2. A dental implant as claimed in claim 1, said milling surfacesbeing separated into a plurality of portions by spaced circular groovesbetween said portions, said grooves being of lesser diameter than saidmilling surfaces.